Portable communications devices (e.g., smart phones) have within them one or more speakers that convert an input electrical audio signal into a sound pressure wave output that can be heard by the user. The speakers can be used to, for example, output sound pressure waves corresponding to the voice of a far end user, such as during a telephone call, or to output sound pressure waves corresponding to sounds associated with a game or music the user wishes to play. Due to the relatively low profile of cellular devices, the speakers also have a relatively low profile, which in turn, can make it difficult to maintain a speaker back volume chamber which allows for maximum sound output in the low frequency ranges. For example, a change in the size of the internal volume of the device housing (such as when a user presses on the device), can have an impact on the speaker within the housing (e.g., increase a surrounding pressure on the speaker), and in some cases, the associated sound output.